Field of the Invention
The invention relates to a viewing device for a stereo projection system, having a first and a second viewing window, each having an optically filtering filter layer system, wherein each viewing window has a filter spectrum in the visual spectral range with a plurality of pass bands that are separated from each other by blocking regions, and wherein each pass band of the filter spectrum of the first viewing window is covered by an associated blocking region of the filter spectrum of the second viewing window.
The invention also relates to a stereo projection system having a projection unit that projects a first and a second image, which represent an object from different viewing angles, onto one another on a projection screen in the visual spectral range with orthogonal projection spectra, and a viewing device that has a first and a second viewing window, each having an optically filtering filter layer system, whose orthogonal filter spectra in the visual spectral range are matched to the projection spectra of the projection unit in such a manner that the first viewing window is transparent for the first projection spectrum and the second viewing window is transparent for the second projection spectrum, wherein each viewing window has a filter spectrum in the visual spectral range with a plurality of pass bands that are separated from each other by blocking regions, and wherein each pass band of the filter spectrum of the first viewing window is covered by an associated blocking region of the filter spectrum of the second viewing window.
Also, the invention relates to a novel use of cyanine dyes in the supramolecular J-aggregate configuration.
Description of the Background Art
The prototype of the so-called wavelength multiplex stereo projection is known from DE 198 08 964 C2.
Various approaches are known for the three-dimensional optical reconstruction of objects. Stereoscopic projection, in particular, has found wide acceptance. In this approach, two sub-images are produced of an object that depict the object from different viewing angles. The difference in angle of view corresponds to the visual parallax of a human observer. To produce a three-dimensional impression of the object, a projection unit and a viewing device in a stereo projection system must interact in such a way that a viewer who is viewing the projected images through the viewing windows of the viewing device sees the sub-image associated with the right eye only with his right eye, and the sub-image associated with the left eye only with his left eye. Different approaches are known to achieve this interaction. In particular, approaches are pursued for temporal, spectral, and/or polarization-related separation of the sub-images. Within the framework of spectral separation of the sub-images, wavelength multiplexing has proven to be especially advantageous, since very good color representation of the object is possible with this method.
In wavelength multiplexing, the two sub-images with mutually orthogonal projection spectra are projected onto a projection screen, for example a movie screen. Within the scope of the present description, orthogonal projection spectra are in general understood to be projection spectra whose spectral bands do not overlap one another in the visible range. In wavelength multiplexing, each projection spectrum comprises multiple spectral bands spaced apart from one another. These bands are preferably oriented toward the location of the spectral sensitivities of the three color receptor types of the human eye. In this context, the bands of the projection spectrum for the right sub-image are offset relative to the bands of the projection spectrum for the left sub-image so that the above described condition of orthogonality of the projection spectra is fulfilled. The sub-images thus produced are projected congruently onto one another on the projection screen. In addition, temporal offsets and/or polarization differences can be provided; however, this leads to a loss of brightness, and is thus undesirable as a general rule. In the cited document, the different projection spectra are achieved through the use of three lasers each, whose wavelengths lie in the red, green, or blue spectral region and are slightly offset from one another in pairs. It is also possible, and known, to generate the projection spectra from a white light source by means of sharp interference edge filters, however.
In order to ensure that the individual sub-images are received separately by the viewer's right and left eyes, a viewing device is provided that has one viewing window for the right eye and another viewing window for the left eye. The viewing windows have different filter spectra, which are orthogonal to one another and are matched to the projection spectra. In particular, the filter spectrum of the viewing window associated with the left eye has pass bands precisely where the bands of the projection spectrum of the left sub-image are located. Conversely, it has blocking regions precisely where the bands of the projection spectrum of the right sub-image are located. The filter spectrum of the viewing window associated with the right eye is designed in the same fashion. The filter spectra of the two viewing windows are orthogonal to one another, where “orthogonal filter spectra” should be understood within the scope of the present description as filter spectra whose pass bands do not overlap with one another. In practice, it will seldom be possible to design the filter characteristics of the viewing windows such that zero transmission is actually present in the blocking region. The concept “not overlapping” must thus be construed functionally with regard to the desired goal of separate perception of the sub-images.
Because of the high contrast sensitivity of the human eye, the selectivity of the filter spectra of the viewing device is of great importance to the quality of a stereo projection system. In order to create suitable viewing windows, the said document proposes coating stiff, transparent carriers with an interference filter layer system. Filters of this nature can be designed precisely and exhibit very sharp pass bands and blocking regions. However, their manufacture is very complex and expensive. Moreover, a stiff carrier is a mandatory requirement, which is disadvantageous with regard to weight and shape adjustment. These disadvantages weigh especially heavily in the customary, eyeglass-like design of viewing devices for stereoscopic cinema projection systems, in which the stereoscopic eyeglasses must be made large enough that they can also be worn over ordinary corrective eyeglasses. In addition, the filter spectrum of interference filters is heavily dependent on the angle of incidence of the light, and hence on the position of the viewer or the reflection location on the screen, both of which are disadvantageous in large movie theaters with a wide screen.
Another disadvantage for the purposes of stereoscopic cinema projection is the durability of the prior art interference filter glasses. In order to amortize the high purchasing costs of stereo projection systems, movie theater operators are forced to charge higher prices for stereoscopic shows than for conventional shows. Psychologically, this is especially easy to implement for the purchase or rental of the stereoscopic glasses. Because of the high costs of conventional interference glasses, this is only practical within the framework of rental. But this entails additional difficulties with regard to theft prevention and hygiene. Disposable, non-reusable eyeglasses that are inexpensive to produce, which would allow the movie theater operator to sell a new pair of glasses to every patron for every show without the need to worry about collecting and cleaning used eyeglasses after every show, would be especially desirable.
A completely different area of optical filter technology is represented by US 2010/0103355 A1, which discloses an LCD display that proposes an additional color correction plate having a filter layer with a J-aggregate of a cyanine dye embedded between two protective layers in order to improve spectral selectivity between the R and G channels and between the G and B channels.